Comments on: Tech FAQ: Solving a Sloppy Spindle http://singletrack.competitor.com/2010/01/bikes-tech/technical-faq/tech-faq-solving-a-sloppy-spindle_5542 Mountain Biking, Bike and Gear Reviews, Race Results, Trails and Singletrack Tue, 31 Jan 2012 05:16:00 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: jjkline http://singletrack.competitor.com/2010/01/bikes-tech/technical-faq/tech-faq-solving-a-sloppy-spindle_5542/comment-page-1#comment-2236 jjkline Thu, 13 May 2010 03:27:57 +0000 http://singletrack.competitor.com/?p=5542#comment-2236 I sent a reply as a guest, but I don't know if it went through so I will repeat it again. I am a machinist by trade and have the same problem Nick has regarding the bottom bracket sloppiness on the non-drive side of the GXP bearing set. I too have nearly identical dimentions Nick described in his question. This appears to be a case of the crankshaft being machined (ground) undersize by .23mm OR bearings that were supplied with bore sizes .23mm oversized. Because of the obvious expense of correcting either, the idea of "pinching" the bearing inner race between the crankshaft shoulder and the left crank arm apparantly was devised. From my point of view this is a totally inappropriate "fix" and does not address the problem of the radial dimension incompatibility causing the excess clearance (.23mm). It seems to me there should be an "undersized" bore bearing available to adequately address the clearance problem. I recenty visited a local velo-swap and discovered three vendors selling cranksets with the exact same problem! I measured their products and found similar faulty dimensions as noted earlier (including the looseness and clunking complaints). I have been in contact with Sram tech support and they have indicated that the "pinching" method should "take care" of the problem...it does not. They have requested a return of the crankset to them for evaluation. I will do so. I also will work on an appropriate fix for the problem at my shop (if Sram does not) and post it here. I must say in closing that I would be embarrassed to send a product out of my shop in the condition this crankset is in...and even more embarrassed to recommend the fix that has been presented in this case.<br><br>Respectfully...JJ Kline I sent a reply as a guest, but I don't know if it went through so I will repeat it again. I am a machinist by trade and have the same problem Nick has regarding the bottom bracket sloppiness on the non-drive side of the GXP bearing set. I too have nearly identical dimentions Nick described in his question. This appears to be a case of the crankshaft being machined (ground) undersize by .23mm OR bearings that were supplied with bore sizes .23mm oversized. Because of the obvious expense of correcting either, the idea of “pinching” the bearing inner race between the crankshaft shoulder and the left crank arm apparantly was devised. From my point of view this is a totally inappropriate “fix” and does not address the problem of the radial dimension incompatibility causing the excess clearance (.23mm). It seems to me there should be an “undersized” bore bearing available to adequately address the clearance problem. I recenty visited a local velo-swap and discovered three vendors selling cranksets with the exact same problem! I measured their products and found similar faulty dimensions as noted earlier (including the looseness and clunking complaints). I have been in contact with Sram tech support and they have indicated that the “pinching” method should “take care” of the problem…it does not. They have requested a return of the crankset to them for evaluation. I will do so. I also will work on an appropriate fix for the problem at my shop (if Sram does not) and post it here. I must say in closing that I would be embarrassed to send a product out of my shop in the condition this crankset is in…and even more embarrassed to recommend the fix that has been presented in this case.

Respectfully…JJ Kline

]]> By: jltruong http://singletrack.competitor.com/2010/01/bikes-tech/technical-faq/tech-faq-solving-a-sloppy-spindle_5542/comment-page-1#comment-1819 jltruong Mon, 08 Feb 2010 18:18:30 +0000 http://singletrack.competitor.com/?p=5542#comment-1819 I have been using my UN-73 bottom bracket for years now and have not experienced any play or slop. :o I have been using my UN-73 bottom bracket for years now and have not experienced any play or slop. :o

]]> By: Jerome http://singletrack.competitor.com/2010/01/bikes-tech/technical-faq/tech-faq-solving-a-sloppy-spindle_5542/comment-page-1#comment-1694 Jerome Wed, 13 Jan 2010 15:02:00 +0000 http://singletrack.competitor.com/?p=5542#comment-1694 Seems to me that you have too many spacers in already. GXP is not like Shimano where you put axial load on both DS and nonDS bearings. The inner race of the nonDS should be clamped between a small shoulder on the spindle and the left crank arm. The inner race of the DS bearing should be under zero axial load. Try removing (if any) spacer between bracket tube and the bearing cups. Seems to me that you have too many spacers in already. GXP is not like Shimano where you put axial load on both DS and nonDS bearings. The inner race of the nonDS should be clamped between a small shoulder on the spindle and the left crank arm. The inner race of the DS bearing should be under zero axial load. Try removing (if any) spacer between bracket tube and the bearing cups.

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